Oven safety control



March 10, 1931. c. L. GEHNRlCH I 1,796,198

OVEN SAFETY CONTROL Filed Sept. 30, 1929 Chavrfes L. Ge/mrich INVENTOR BY WF 4 4 Md ATTORNEY Patented Mar. 10, 1931 UNITED STATES PATENT OFFICE CHARLES L. GEHNRIGH, ELMHURST, NEW YORK, ASSIGNOR TO GEHNRICH OVEN CO., INC., OF LONG ISLAND CITY, NEW YORK, A CORPORATION OF NEW YORK OVEN SAFETY CONTROL Application filed September 30, 1929. Serial No. 396,168.

10 fact, when the oven becomes hotter an explosion will take place. Such explosions are very frequent in this art and have been the source of much trouble and expense.

The principal object of this invention is to eliminate all hazard in baking materials which emit combustible vapors by the provision of positive exhaust at all times when heat is on and maximum exhaust during the period when combustible vapors are given off. .As a necessaryincident to the perfect fulfilment of this object I provide means for shutting off the heat supply in case anything should happen to prevent the desired speed of exhaus A further object of my invention is to automatically reduce the exhaust to practical requirements for the conservation of heat after the combustible vapors are removed.

Another object of my invention is to provide means for automatically cutting ofi all heat supply when the oven door is opened for any reason.

A still further object of my invention is to so arrange the parts of my device that in case the oven door is opened thereby shutting off the heat before the aforesaid maximum exhaust period is ended, said maximum exhaust period will be started anew on the closingof the door. This provision is a safeguard against those situations where a workman opens the oven door before the maximum exhaust period is ended in order to put in fresh material tobe baked. If only the remainder of the maximum exhaust period were to be allowed on the closing of the door, there would not be suflieient time for the combustible vapors from the new material to be removed from the oven and an explosion would result.

Further objects and advantages of my invention Will appear from the detailed description of the accompanying drawing which is a vertical section through an oven equipped with the aforesaid means. Referring more specifically to said drawings, 1 represents an oven of the usual construction having a door 2 and gas circulating pipe 3 connected. to a fan 4 which is operated by an electrical motor, not shown, which is energized by a mag netic starter 5. The oven has the usual screened air-inlet 18 near the base which is'a conventional construction common to every oven. There can be as many of these and in such position as desired. Gases are with drawn from the oven by the fan through the pipe 6 and returned or exhausted through the pipe 7. Between the fan and the pipe 7 is a horizontal pipe 8. It is to be understood, however, that these pipes may be placed in any plane or at any angle to each other without departing from the scope of my invention.

Pivoted in the pipe 7 adjacent the junction of the same with the pipe 8 is a damper 9 adapted to connect the pipe 8 with the interior of the oven or with the atmosphere as desired. Or the damper 9 may be so adjusted that part of the efliuent gases return to the oven and part go off into the atmosphere. This adjustment is made possible by means of a screw 10 mounted on the pipe"? and capable of being projected into the path of the damper 9. On the inner end of the damper 9 is a weight 11 which tends to hold the dam er 9 in a position to prevent the return 0 the efli'uent gases to the oven and to insure complete exhaust to the outside. Of course it is obvious that this weight can be placed on the outer end of the damper to normally hold said on the outer end of the damper the time relay switch used is one which opens the solenoid circuit after a predetermined interval. Gonnected in series with the solenoid circuit is a switch 15, one contact of which is on the oven wall and the other contact of which is on the oven door whereby when the oven door isv not removed from the oven. In such a case if heat were applied to the oven continuously an explosion would take place. In order to safeguard against such a possibility a safety switch 17 is inserted in the pipe 8. The switch consists of a vane suspended in said pipe and adapted to be swung into circuit-closing position by the draft in said pipe. This switch is in series with the heating circuit whereby when, for any reason, the draft in pipe 8 ceases, the vane assumes an upright position and breaks the heating circuit.

The operation of my device is very simple. When the oven door is closed, thereby starting-the fan motor and subsequently closing the heating circuit, the damper 9 is held by weight 11 in a position to force all the efiiuent gases. into the atmosphere. The time relay switch 14 is set so as to close after an interval predetermined to be suflicient to rid the oven of combustible gases. After this interval has elapsed switch .14 closes, thereby energizing the solenoid 12 which moves damper 9 to a position regulated by the screw 10. This position is mainl determined by the ventilation desired in t e oven and is usually such that, while the material to bebaked is being .dried, the efliuent gases are completely removed from the oven while they contain vapor in explosive proportions. It is to be understood that if weight 11 be placed on the outer end of the dam er the action is reversed. That is, the so enoid circuit is closed upon the closin of the oven door and the energized solenoid holds the damper open by overcoming the force of weight 11. The time rela being of the type which opens after a pre etermined interval, breaks the solenoid circuit after said interval whereby said damper is closed to the desired position by weight 11. The rate of exhaust can be regulated by totally closing the hand damper 16 and ad usting the damper 9 so as to permit any desired quantity of gas to escape. As before stated, if for any reason the fan should fail to function, the safety switch 17 will cut off the supply of heat. Likewise, if the oven door should open for an reason, the heating supply would be out o It is to be understood that there is no electrical connection be tween the heating circuit and the oven door Having thus described the nature and ob- -jects of my invention and illustrated a preferred. embodiment of the same, which embodiment, however, is to be taken as illustrative rather than limitative, what I claim as new and desire to secure by Letters Patent 1s:

1. In an oven for baking materials giving off combustible gases, in combination, an outlet pipe for withdrawing gases from said oven, an inlet pipe connected with said outlet pipe for returning said gases to said oven, a damper for alternately connecting said outlet pipe with the atmosphere and with said inlet pipe, and means for causing said damper to connect said outlet pipe completely with the atmosphere for a predetermined period at the beginning of the bake.

2. In an oven for baking materials giving off combustible gases, in combination, an outlet pipe for withdrawing gases from said oven, an inlet pipe connected with said outlet pipe for returning said gases to said oven, a damper for alternately connecting said outlet pipe with the atmosphere and with said inlet pipe, means for causingsaid damper to connect said outlet pipe completely with the atmosphere for a predetermined period at the beginning of the bake, and means for automatically moving said damper at the end of said predetermined eriod.

3. In an oven for ba ing materials giving off combustible ases, in combination, an outlet pipe for withdrawing gases from said oven, an inlet pipe connected with said outlet pipe for returning said gases to said oven, a damper for alternately connecting said outlet pipe with the atmosphere and with said inlet pipe, means for causing said'damper to connect said outlet pipe completely with the atmosphere for a predetermined period at the be inning of the bake, means for automatica y moving said damper at the end of said predetermined period, and means for regulating the movement of said damper.

- 4. In an oven for baking materials giving off combustible gases, in combination, an outlet pipe for withdrawing gases from said oven, an inlet pipe connected with said outlet pipe for returning said gases to said oven, a solenoid damper for alternately connecting said outlet pipe with the atmosphere and with said inlet pipe, and a weight acting on'said source of power, a solenoid damper for alternately connectin said outlet pipe with the atmosphere and wit said inlet plpe, a weight for causing said damper to connect said out let pipe completely with the atmosphere for a predetermined period at the be inning of the bake, and a time relay switc for connecting said solenoid to said source of power at the end of said predetermined period whereby said solenoid is energized and moves said damper.

6. In an oven for baking materials giving off combustible gases, in combination, an outlet pipe for withdrawing gases from said oven, an inlet pipe connected with said outlet pipe for returning said gases to said oven, 21 source of power, a solenoid damper for alternately connecting said outlet pipe with the atmosphere and with said inlet pipe, a weight for causing said damper to connect said outlet pipe completely with the atmosphere for a predetermined period at the beglnning of the bake, a time relay switch for connecting said solenoid to said source of ower at the end of said predetermined period whereby said solenoid is energized and moves said damper, and means for regulating the distance moved by said damper.

7. In an oven for baking materials giving ofi combustible gases, in combination, an outlet pipe for withdrawing gases from said oven, an inlet pipe connected with said outlet pipe for returning said gases to said oven, a

' source of power, a solenoid damper for alternately connecting said outlet pipe with the atmosphere and with said inlet pipe, a weight for causing said damper to connect said outlet pipe completely with the atmosphere for a predetermined period at the be ginning of the bake, a time relay switch for connecting said solenoid to-said source of of the outlet pipe therewith having a portion extending outslde said inlet pipe, means on its inner end to normally close said junction, and electrical means on said extended por-- tion for automaticall opening said junction after a predetermine eriod.

10. In an oven having an outlet pipe for withdrawing gases therefrom and an inlet pipe connected with said outlet pipe for returnin said gases to said oven, a damper pivote in said inlet pipe opposite the junction of the outlet pipe therewith having a portion extending outside said inlet pipe, a weight on its inner end to normally close said junction, and electrical means on said extended portion for automatically opening said junction after a predetermined period.

11. In an oven having an outlet pipe for withdrawing gases therefrom and an inlet pipe connected with said outlet pipe for returning said ases to said oven, a damper pivoted in said inlet pipe opposite the junction of the outlet pipe therewith having a portion extending outside said inlet pipe, a weight on its inner end to normally close said junction, and a solenoid on said extended portion for automatically opening said junction after a predetermined period.

In testimony whereof I have hereunto set my hand.

CHARLES L. GEHNRICH.

power at the end of said predetermined pe- 1 riod whereby said solenoid is energized and moves said damper, and a switch operated by the oven door in series with, said time relay switch whereby, when said oven door is opened during said predetermined period, said. period begins anew upon the closing of said oven door.

8. In an oven having an outlet pipe for withdrawing gases therefrom and an inlet pipe connected with said outlet pipe for re turning said gases to said oven, a damper pivoted in said inlet pipe opposite the unction of the outlet pipe therewith having a portion extending outside said inlet pipe, means on its inner end to normally close said junction, and means on said extended portion for antomatically opening said junction after a predetermined period.

9. In an oven having an outlet pipe for withdrawing gases therefrom and an inlet pipe connected with said outlet ipe for returning said gases to said oven, a am er pivoted in said inlet pipe opposite the unction 

